(a) Field of the Invention
This invention relates to a casting method, and, more particularly, to a method of casting that is particularly suitable for incorporating other casting component into a cast article.
(b) Prior Art
So called internal chill techniques have heretofore been practiced to incorporate into a predetermined part of a cast article other component members in accordance with the purpose of use of the cast article. For these internal chill techniques, there have been known mechanical internal chill methods, in which the component to be incorporated is simply held in the cast article by a mechanical expedient, and in other internal chill technique in which diffusion reaction is accompanied by various kinds of treatment. In either of these cases, the process requires many steps and has high cost of treatment, despite which the resulting cast article does not have sufficient mechanical strength and its range of use is considerably limited. For example, in the case of an aluminum alloy casting, various ferrous materials which have been subjected to a plating process with molten aluminum (the so-called "aluminizing treatment") have been utilized as the internal chill member. This internal chill member, however, is low in its adhesive strength to a matrix metal alloy; hence, in many cases, mechanical means for joining both together has been resorted to in general. Furthermore, this internal chill member brings about serious problems in its thermal expansion difference and its use in hot conditions with respect to aluminum alloy having a heat-treatable property. In addition, the combination of these two metal materials requires complicated process steps, and hence is inferior in its productivity in an industrialized large scale while being costly in its manufacture.
On the other hand, with increasingly wide use of ceramic materials in many fields of industry, there have been increasing demands toward the internal chill joining of this material making best use of its physical characteristics. At the present circumstances, however, there is no effective method for incorporating other component member to the ceramic material other than the mechanical internal chill method, and hence its range of use is limited as is the case with the above-mentioned aluminum alloy casting.